package com.test.servlet;

import javax.servlet.ServletException;
import javax.servlet.ServletOutputStream;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.FileInputStream;
import java.io.IOException;
import java.net.URLEncoder;

public class FileServlet extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        //1.要获取下载文件的路径
        String  realPath = "D:\\JavaLearn\\Project\\JavaWeb\\JavaWeb-pro\\Response-test-01\\src\\main\\resources\\img1.jpg";
        System.out.println("下载文件的路径：" + realPath);

        //2.下载的文件名是啥？
        String fileName = realPath.substring(realPath.lastIndexOf("\\") + 1);  //可以巧妙获取文件名

        //3.设置让浏览器支持(Content-Disposition)下载我们需要的东西,中文文件名URLEncoder.encode编码，否则有可能乱码
        resp.setHeader("Content-Disposition","attachment;filename=" + URLEncoder.encode(fileName, "UTF-8"));

        //4.获取下载文件的输入流
        FileInputStream fileInputStream = new FileInputStream(realPath);

        //5.创建缓冲区
        int len = 0;
        byte[] buffer = new byte[1024];

        //6.获取OutputDtream对象
        ServletOutputStream servletOutputStream = resp.getOutputStream();

        //7.将FileOutputStream流写入到buffer缓冲区
        //8.使用OutputStream将缓冲区中的数据输出到客户端
        while((len = fileInputStream.read(buffer)) > 0){
            servletOutputStream.write(buffer,0,len);
        }
         servletOutputStream.close();
        fileInputStream.close();
    }

    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        doGet(req, resp);
    }
}
